1. Field of the Invention
The present invention relates to an ink container and an image forming apparatus including the ink container, and more specifically, to an ink container provided in an image forming apparatus such as an inkjet copying machine, an inkjet facsimile machine, an inkjet printer or the like and integrally formed with a head that discharges ink; and the image forming apparatus including the ink container.
2. Description of the Related Art
For many cases, in an inkjet image forming apparatus such as an inkjet copying machine, an inkjet facsimile machine, an inkjet printer or the like, a head discharges ink downward onto a recording medium such as a recording paper (for example, see Patent Document 1 to Patent Document 5). In some cases, in an inkjet image forming apparatus, a head discharges ink in a lateral direction or in an inclined direction (for example, see Patent Document 6).
Further, for such an inkjet image forming apparatus, a structure is known where a cap is provided on a discharging surface of the head in order to prevent drying of the ink (for example, see Patent Document 1 to Patent Document 4). When the head is the type that discharges the ink downward onto the recording medium, the cap caps the head in the upper direction and the ink usually does not leak from the cap even when the ink becomes attached to the cap. However, when the head is the type that discharges the ink in the lateral direction or in the inclined direction, the ink attached to the cap may leak and may contaminate the inside of the image forming apparatus.
Therefore, as for the image forming apparatus in which the head discharges the ink in the lateral direction or in the inclined direction, it may be considered to rotate the head to face downward to be capped with a cap facing upward when capping the head. Thus, there is a case when it is desirable to structure the image forming apparatus such that the position of the head is changeable based on the situation.
On the other hand, a technique to detect the amount of the ink in the ink reservoir which is integrally formed with the head using the conductivity of the ink for appropriately adjusting the amount of the ink in the ink reservoir is known (for example, see Patent Document 1 to Patent Document 7).
Further, a structure where the ink container is a sub tank is also known (for example, see Patent Document 1 to Patent Document 4). The sub tank receives the ink supplied from the ink cartridge, which is the main tank, via a tube or the like. The sub tank functions as a reservoir tank so that the formation of an image can be performed even after the ink cartridge becomes empty. Further, the sub tank may function as a negative pressure forming unit for preventing the leakage of the ink from the head.
However, when the position of the head is changeable, even when the amount of the ink can be detected by the conventional technique to detect the amount of the ink at one position, the amount of the ink cannot be properly detected by the conventional technique at another position.